Mother substrate for producing display device

ABSTRACT

A method for producing a display device includes forming a resin film on a substrate, forming a plurality of light emitting elements above the resin film, forming a plurality of first grooves in a surface of the resin film, the plurality of first grooves enclosing the plurality of light emitting elements individually in a multiple-fold manner, cutting the substrate at a position overlapping any one of the plurality of first grooves other than the first groove closest to one of the plurality of light emitting elements, and peeling off the substrate from the resin layer.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.14/660,118, on Mar. 17, 2015, which claims the benefit of priority fromthe Japanese Patent Application No. 2014-071677, filed on 31 Mar. 2014,the entire contents of which are incorporated herein by reference.

FIELD

The present invention relates to a display device and a method forproducing the same, and specifically to a sheet display device includinga panel using a resin film as a substrate.

BACKGROUND

In general, in order to form a large number of sheet display devicessuch as organic EL display devices or the like by use of a mothersubstrate, the following method is used. A resin film formed ofpolyimide or the like is formed on the mother substrate, and a pluralityof organic EL elements including a plurality of thin film transistors(TFTs), a light emitting layer and ages barrier layer are formed on theresin film. Then, the substrate is cut into a plurality of substrateportions by a glass scribe method or the like, and the resin film ispeeled off from the substrate portions to produce a plurality of organicEL display devices. As such a mother substrate, a glass substrate isused, for example.

However, the resin film is thin and elastic, and cannot be easily cuttogether with the glass substrate by the glass scribe method. It is noteasy either to peel off the resin film from the glass substrate.Therefore, there is a problem that in a step of cutting the glasssubstrate or a step of peeling off the resin film from the glasssubstrate, the resin film formed on the glass substrate is pulled, whichdamages the TFTs and the organic EL elements formed on the resin film.

In addition, it is difficult to make small the tolerance for the cuttingposition at which the glass substrate is to be cut. For these reasons, aproduction method capable of enlarging the margin for the cuttingposition of the glass substrate and thus providing a high yield isdesired.

According to an existing method proposed for this purpose, a groove isformed by laser light in a resin film along a line along which the glasssubstrate is to be cut before the glass substrate is actually cut, andthen a scribing unit is directed to the groove formed on the resin filmin order to cut the glass substrate by the scribe method.

With reference to FIG. 1 and FIG. 2, an example of such a method forproducing a conventional organic EL display device will be described. Asshown in FIG. 1A, a first resin film 20 is formed on a first glasssubstrate 10, which is a TFT-side mother substrate. An organic EL layer40, a sealing member 44, a filling member 42, a line 30 and the like areformed on the first resin film 20. A second resin film 22 is formed on asecond glass substrate 12, which is a counter substrate-side mothersubstrate. On the second resin film 22, a gas barrier layer 24 may beformed. Although not shown, ages barrier layer may also be formed on thefirst resin film 20.

From the structure shown in FIG. 1A, individual organic EL displaydevices are produced as follows, for example. First, from the stateshown in FIG. 1A, an interface between the second glass substrate 12 andthe second resin film 22 is irradiated with laser light to remove thesecond glass substrate 12.

Next, as shown in FIG. 1B. the first resin film 20 and the second resinfilm 22 are irradiated with light from a solid UV laser to cut the firstresin film 20 and the second resin film 22.

Next, as shown in FIG. 1C, an excessive portion of the first resin film20 and the second resin film 22 is removed.

Next, as shown in FIG. 2A and FIG. 2B, an excessive, portion of thefirst glass substrate 10 (on the TFT side) is cut away by the glassscribe method.

Next, an interface, between the first glass substrate 10 and the firstresin film 20 is irradiated with laser light to remove the first glasssubstrate 10.

As a result, individual organic EL display devices 1000 as shown in FIG.2C are produced.

For example, Japanese Laid-Open Patent Publication No. 2011-227369describes the following. In a resin film provided on a mother substrate,one groove along which the resin film is to be out is formed. After themother substrate is peeled off, a plastic substrate is bonded to theresin film. Then, the plastic substrate is cut along the groove formedin the resin film.

According to this method, only one groove is formed in the resin film.Therefore, there is a problem that in the case where the cuttingposition at which the glass substrate is cut is offset, the resin filmis pulled, which may damage display elements formed on the resin film.

SUMMARY

A method for producing a display device according to the presentinvention includes forming a resin film on a substrate; forming aplurality of light emitting elements above the resin film; forming aplurality of first grooves in a surface of the resin film, the pluralityof first grooves enclosing the plurality of light emitting elementsindividually in a multiple-fold manner; cutting the substrate at aposition overlapping any one of the plurality of first grooves otherthan the first groove closest to one of the plurality of light emittingelements; and peeling off the substrate from the resin layer.

In the method for producing a display device according to the presentinvention, the plurality of first grooves may be formed in a latticepattern enclosing the light emitting elements individually in amultiple-fold manner.

In the method for producing a display device according to the presentinvention, the plurality of first grooves may be formed in a rectangularor square pattern enclosing the light emitting elements individually ina multiple-fold manner.

The method for producing a display device according to the presentinvention may further include forming a plurality of second groovessubstantially perpendicular to the plurality of first grooves.

The method for producing a display device according to the presentinvention may further include forming a gas barrier layer on the resinfilm.

In the method for producing a display device according to the presentinvention, a member including a SiN layer and a SiO₂ layer stacked inthis order may be formed as the gas barrier layer on the resin film.

In the method for producing a display device according to the presentinvention, a member including a SiO₂ layer, a SiN layer and another SiO₂layer stacked in this order may be formed as the gas barrier layer onthe resin film.

In the method for producing a display device according to the presentinvention, the resin film may be a polyimide film.

The method for producing a display device according to the presentinvention may further include forming a flexible printed circuitconnected to the TFT layer.

The method for producing the organic EL display device according to thepresent invention having the above-described structure allow the marginfor a cutting position of the substrate to be enlarged and thus preventdisplay elements from being damaged in the step of cutting thesubstrate.

BRIEF EXPLANATION OF DRAWINGS

FIG. 1A through FIG. 1C are each a schematic cross-sectional viewprovided to describe a method for producing a conventional organic ELdisplay device;

FIG. 2A through FIG. 2C are each a schematic cross-sectional viewprovided to describe the method for producing the conventional organicEL display device;

FIG. 3A through FIG. 3C are each a schematic cross-sectional viewprovided to describe a method for producing an organic EL display deviceaccording to the present invention;

FIG. 4A through FIG. 4C are each a schematic cross-sectional viewprovided to describe the method for producing the organic EL displaydevice according to the present invention;

FIG. 5 is a schematic plan view provided to show a step shown in FIG. 4Ain an example, of method for producing the organic EL display deviceaccording to the present invention;

FIG. 6 is a schematic plan view provided to show a step shown in FIG. 4Ain another example of method for producing the organic EL display deviceaccording to the present invention; and

FIG. 7 is a schematic plan view provided to show a step shown in FIG. 4Ain still another example of method for producing the organic EL displaydevice according to the present invention.

DESCRIPTION OF EMBODIMENTS

The present invention has an object of providing a method for producinga display device by which a margin for a cutting position of a substrateis enlarged and thus display elements are prevented from being damagedin a step of cutting the substrate.

Hereinafter, a method for producing an organic EL display device in eachof embodiments according to the present invention will be described withreference to the drawings. The present invention is not limited to anyof the following embodiments, and may be carried out in any of variousembodiments without departing from the gist thereof.

(Embodiment 1)

With reference to FIG. 3 through FIG. 7, embodiment 1 according to thepresent invention with be described. FIG. 3 and FIG. 4 show schematiccross-sectional views provided to describe a method for producing anorganic EL display device according to the present invention. FIG. 5through FIG. 7 are each a schematic plan view of a mother substrate in astep shown in FIG. 4A in an example of method for producing the organicEL display device according to the present invention.

In this embodiment, as shown in FIG. 3A, a first resin film 200 and asecond resin film 220 are respectively formed on a first glass substrate100 and a second glass substrate 200. On the second resin film 220, agas barrier layer 240 is formed. Although not shown, a gas barrier layermay also be formed on the first resin film 200. Between the first resinfilm 200 and the second resin film 220, an organic EL layer 400, asealing member 440, a filling member 420, a line 300 and the like, whichare included in a plurality of organic EL display devices, are formed.

A specific structure of the gas barrier layer 240 is not shown. Forexample, the gas barrier layer 240 may include a SiN layer and a firstSiO₂ layer stacked in this order from the side of the second resin film220. Alternatively, the gas barrier layer 240 may include a second SiO₂layer, a SiN layer and a first SiO₂ layer stacked in this order from theside of the second resin film 220.

A specific structure of the organic EL layer 400 is not shown. Theorganic EL layer 400 may roughly include a layer in which a TFT (thinfilm transistor) is to be formed (TFT layer) and a layer in which anorganic light emitting diode is to be formed (OLED layer). In thisembodiment, the OLED layer corresponds to an organic EL element. The TFTlayer may be formed, for example, by a usual LTFS (Low TemperaturePoly-Silicon) method. A semiconductor layer used for the TFT layer maybe formed of amorphous silicon, an oxide semiconductor, or an organicsemiconductor.

The first glass substrate 100 and the second glass substrate 200 areeach a mother substrate, and can have a plurality of organic EL displaydevices formed thereon. The first glass substrate 100 is a mothersubstrate on the side where the TFT is formed, and the second glasssubstrate 200 is a mother substrate on the side where a countersubstrate is formed. In FIG. 3A, a pair of mother substrates, morespecifically, the first glass substrate 100 and the second glasssubstrate 200, are used for the production of the organic EL displaydevices. Alternatively, the second glass substrate 200 may be omitted.

The first resin film 200 and the second resin film 220 may be each, forexample, a polyimide film. Polyimide withstands a process temperatureused for forming a TFT thereon by the LTPS (Low TemperaturePoly-Silicon) method or the like, and thus is preferable as a materialof the resin films 200 and 220 according to the present invention.

In a step shown in FIG. 3A, the first resin 200 and the second resinfilm 220 are irradiated with laser light to form a plurality of grooves.A preferable processing precision at which the plurality of grooves areformed in the first resin film 200 and the second resin film 220 bylaser light is 0.1 mm to 0.3 mm.

The plurality of grooves formed in the first resin film 200 and thesecond resin film 220 may be of any pattern that encloses the pluralityof organic EL display devices individually in a multiple-fold manner.

For example, as in a mother substrate 3000 shown in FIG. 5, theplurality of grooves may include a plurality of sets of first grooves,each of the sets including three first grooves 1 a, 1 b and 1 cgenerally parallel to one another, and a plurality of sets of firstgrooves, each of the sets including three first grooves 1 d, 1 e and 1 fgenerally perpendicular to the first grooves 1 a, 1 b and 1 c. The setsof first grooves 1 a, 1 b and 1 c and the sets of first grooves 1 d, 1 eand 1 f may be provided in a lattice pattern so as to enclose theorganic EL display devices individually in a multiple-fold manner.

As in a mother substrate 3100 shown in FIG. 6, the plurality of groovesmay include a plurality of sets of first grooves, each of the setsincluding three first grooves 1 g, 1 h and 1 i. The three first grooves1 g, 1 h and 1 i may be of rectangular or square patterns similar to oneanother with different sizes, and the sets of first grooves 1 g, 1 h and1 i may enclose the organic EL display devices individually in amultiple-fold manner.

As in a mother substrate 3200 shown in FIG. 7, the plurality of groovesmay include a plurality of sets of three first grooves 1 a, 1 b and 1 cand a plurality of sets of three first grooves 1 d, 1 e and 1 f that areprovided in a lattice pattern so as to enclose the organic EL displaydevices individually as shown in FIG. 5, and may also include aplurality of sets of second grooves substantially perpendicular to thefirst grooves. For example each of the sets may include second grooves 2a, 2 b, 2 c, 2 d and 2 e that are substantially perpendicular to thefirst grooves 1 a, 1 b, 1 c, 1 d, 1 e and 1 f.

In this embodiment, as shown in FIG. 5 through FIG. 7, a plurality ofgrooves are formed in the glass substrate, and the glass substrate iscut along a cutting line, which is any of the grooves other than thegroove closest to each of the organic EL display devices. As a result,even if there is a variance in actual cutting lines used to cut theglass substrate by the glass scribe method or the like, for example,even if an actual cutting line is offset toward the organic EL displaydevice (inward), the resin film has at least one groove inner to theactual cutting line (on the side of the organic EL display device).Therefore, the damage caused when the glass substrate is cut is absorbedby the groove(s) provided inner to the cutting line and does notinfluence an area inner to such groove(s). Thus, the margin for thecutting position of the glass substrate is enlarged. In addition, thedisplay elements are suppressed from being damaged in the step ofcutting the glass substrate.

As shown in FIG. 7, the second grooves are provided. In this structure,the first grooves are divided into short portions by the second grooves.Therefore, even if in a step of irradiating the surface of the resinfilm with laser light to form the plurality of first grooves, the amountof the laser light is insufficient and thus a part of the first groovesis not sufficiently deep, the damage caused by cutting the glasssubstrate by the glass scribe method does not influence an area of theresin film that is other than the short portions of the first groovesseparated from each other by the second grooves.

In this manner, the plurality of grooves is formed in the first resinfilm 200 and the second resin film 220. Next, in a step shown in FIG.3B, the second glass substrate 120 on the counter substrate side is cutby the glass scribe method to remove an excessive portion of the secondglass substrate 120.

Then, in the step shown in FIG. 3B, an interface between the secondglass substrate 120 on the counter substrate side and the second resinfilm 220 is irradiated with laser light to peel off the second glasssubstrate 120.

As shown in FIG. 3C, the second glass substrate 120, which has beenpeeled off, is removed.

Next, as shown in FIG. 4A, an excessive portion of the second resin film220 is removed.

Next, as shown in FIG. 4B and FIG. 40, ascribing unit is directed to anyof the plurality of first grooves other than the innermost first groovein order to cut the first glass substrate 100 on the TFT side by thescribe method. Then, an interface between the first glass substrate 100and the first resin film 200 is irradiated with laser light to peel offthe first glass substrate 100. The first glass substrate 100 and anexcessive portion of the first resin film 200 are removed.

As a result, organic EL display devices 2000 as shown in FIG. 40 areproduced.

According to the organic EL display device, and the method for producingthe same in this embodiment described above, a plurality of grooves areformed in the resin film and the substrate is cut along a cutting line,which is any of the plurality of grooves other than the groove closestto the organic EL display device. Therefore, even if there is a variancein actual cutting lines used to cut the glass substrate by the glassscribe method or the like, for example, even if an actual cutting lineis offset toward the organic EL display device (inward), the resin filmhas at least one groove inner to the actual cutting line (on the side ofthe organic EL display device). Therefore, the damage caused when theglass substrate is cut is absorbed by the groove(s) provided inner tothe cutting line and does not influence an area inner to such groove(s).Thus, the margin for the cutting position of the glass substrate isenlarged. In addition, the display elements are suppressed from beingdamaged in the step of cutting the glass substrate. In this manner, theorganic EL display device and the method for producing the same in thisembodiment allow the margin for a cutting position of the substrate tobe enlarged and thus prevent the display elements from being damaged inthe step of cutting the substrate.

(Embodiment 2)

In embodiment 2 according to the present invention, the TFT layerincluded in the organic EL layer 400 is connected to a flexible printedcircuit (FPC).

The other elements and effects of embodiment 2 according to the presentinvention are substantially the same as those of embodiment 1 describedabove and will not be repeated.

What is claimed is:
 1. A mother substrate for producing a display devicecomprising: a substrate; a resin film on the substrate; a plurality oflight emitting elements above a first surface of the resin film oppositeto a second surface of the resin film in contact with the substrate; anda plurality of first grooves in a surface of the resin film, whereineach of the plurality of light emitting elements is enclosed by theplurality of first grooves individually in a multiple-fold manner, andthe plurality of first grooves are configured so as to not overlap witheach of the plurality of light emitting elements in a plan view and in across-sectional view.
 2. The mother substrate for producing the displaydevice according to claim 1, wherein the plurality of first grooves arearranged in a lattice pattern enclosing the light emitting elementsindividually in a multiple-fold manner.
 3. The mother substrate forproducing the display device according to claim 1, wherein the pluralityof first grooves are arranged in a rectangular or square patternenclosing the light emitting elements individually in a multiple-foldmanner.
 4. The mother substrate for producing the display deviceaccording to claim 1, further comprising a plurality of second groovesintersecting substantially perpendicular to the plurality of firstgrooves.
 5. The mother substrate for producing the display deviceaccording to claim 1, wherein at least three first grooves are betweentwo adjacent light emitting elements.